Human IL-4 ELISA
The IL-4 ELISA is to be used for the in-vitro quantitative determination of interleukin-4. (IL-4) in human serum, plasma, buffered solutions or cell culture medium. The assay will recognize both natural and recombinant human IL-4.
IL-4 is a lymphokine that co-stimulates the proliferation of activated B- and T-cells, augments the cytotoxic activity of lymphocytes and monocytes and enhances the functionnal activity of myeloid cells (1). Produced by mast cells, T-cells and bone marrow stromal cells, IL-4 regulates the differentiation of naive CD4+ cells into helper Th2 cells characterized by their cytokine secretion-profile that includes secretion of IL-4, IL-5, IL-6, IL- 10 and IL-13 which favor a humoral immune response (2.3). In addition, IL-4 can inhibit the proliferation of TNF, IL-1 and IL-6 by macrophages (4.5)
IL-4 induces B-cell class switching to IgE and IgG1 isotypes, and up regulates MHC Class II production and CD23 expression (6)
IL-4 is a 15kDa globular glycoprotein containing 129 amino acid residues. The non glycosylated form of the protein is fully biogically active.(7)
A monoclonal antibody specific for IL-4 has been coated onto the wells of the microtiter strips provided.
During the first incubation, IL-4 present in the sample or standard bind to the antibody coated.
Following incubation IL-4 is removed during a wash step. A monoclonal anti IL-4 antibody conjugated to biotin is then incubated. Following incubation unbound biotinylated anti-IL-4 is removed during a wash step.
Streptavidin-HRP is added and binds to the biotinylated anti IL-4. After incubation and a wash step a substrate solution reactive with HRP is added to the wells.
A coloured product is formed in proportion to the amount of IL-4 present in the sample. The reaction is terminated by addition of acid and absorbance is measured at 450 nm.
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